1. Field of the Invention
This invention relates to an improved coolant seal for a seal assembly of the type employed in oil film bearings in rolling mills.
2. Description of the Prior Art
A previously developed sealing arrangement for a rolling mill oil film bearing is shown in FIG. 1. In this arrangement, as described in U.S. Pat. No. 4,455,856 (Salter, et al), the roll 10 has an end face 12 joined by an intermediate tapered section 14 to a reduced diameter section 16 surrounded by a sleeve 18. The sleeve is keyed or otherwise secured to the roll neck, and is journalled in a bushing 20 fixed within a roll chock 22. Oil is supplied continuously at the bearing interface between the sleeve and bushing. A seal assembly generally indicated at 24 surrounds the intermediate tapered roll neck section 14. The seal assembly prevents oil from escaping from the bearing and also prevents contaminants such as cooling water, mill scale, etc. from penetrating into the bearing.
The seal assembly includes a circular flexible flanged neck seal 26, a flinger ring 28, a seal end plate 30 and a coolant seal 32. The neck seal 26 and flinger ring 28 are carried on and rotate with the roll neck, whereas the seal end plate 30 and coolant seal 32 remain fixed in relation to the bearing chock 22.
The coolant seal 32 has a radial base flange 34 integrally joined at its inner edge as at 36 to a sealing flange 38 extending angularly therefrom. Flange 38 terminates in a relatively sharp sealing lip 39 sealingly contacting the roll end face 12. The base flange has holes 40 through which protrude screws 42 which are threaded into the seal end plate 30. The base flange 34 has an integral circular shoulder 44 which protrudes axially towards the roll end face 12, and which acts as a bumper against which the roll end face may bear during an extreme axial "floating" of the roll in relation to the chock.
While this arrangement has the capability of operating in a generally satisfactory manner, it does embody several drawbacks. For example, when the roll moves axially towards the seal end plate 30, the sealing lip 39 undergoes a substantial radial expansion from its original diameter D.sub.1 to an enlarged diameter D.sub.2. This produces a substantial hoop stress at the sealing lip 39 which causes it to bear against the roll end face 12 with increased pressure. This increased pressure generates increased heat and friction and accelerates wear of the sealing lip. Moreover, under extreme conditions, as illustrated for example in FIG. 2, the increased hoop stress can cause the sealing flange to "belly out" as at 44. This further increases friction, heat and wear of the sealing flange. Also, at locations between the screws 42, the increased hoop stress can pull the base flange 34 away from the end of the seal end plate, thereby opening up spaces 46 through which coolant and entrained contaminants can penetrate into the bearing.